Adhesion of organs is one of the complications after open surgery such as in abdominal surgery or gynecology. Adhesion means a reformation with different organs wrongly contacting each other, sometimes caused in a wound healing process after a surgical operation although the organs should not contact each other in a normal situation. The adhesion which is often caused in an open surgery is usually asymptomatic. However, the adhesion might cause a serious complication such as pain, ileus and infertility although its frequency is low.
Once an adhesion is caused in a part, it cannot be treated noninvasively. So, the adhesion must be exfoliated by a surgical treatment when it has a serious complication such as ileus. Therefore, it is very important to appropriately treat a wounded part to not cause adhesion after the first operation.
Adhesion-preventing materials such as silicone, “TEFLON” (registered trademark) and polyurethane have been conventionally used to physically separate organs. However those materials are non-absorbable materials so that they remain on a biotissue surface as causing infection or inflammation as well as delaying tissue restoration.
To solve those problems, JP 2004-065780 A and JP 2001-192337 A disclose recent reports of adhesion-preventing materials made of natural macromolecules such as gelatin and collagen which are expected to be bioabsorbable. However, the gelatin or collagen should not be used in vivo because the antigenic telopeptide of gelatin and collagen can hardly be removed while they might cause a biological infection derived from prion contaminant. Further, cross-linkers to be added to enhance a strength and control the degradability should not be used in vivo in most cases.
The natural macromolecules might have poor strength although they have a high affinity to skin. Therefore, it has been necessary to make a cross-linked body with a cross-linker or ensure strength of the natural macromolecules with reinforcing material, wrapping gauze or the like. However, the reinforcing material might be impractical because of its complicated structure.
JP 2003-153999 A discloses a report of adhesion-preventing material comprising polysaccharides such as trehalose and sodium alginate having less risk of infection. However, a film material of polysaccharide might be impractical because it doesn't have a strength enough to firmly cover a wounded part without breakage or the like. WO 2005/094915 discloses a report of adhesion-preventing materials using hyaluronic acid. Although the soluble hyaluronic acid absorbs water in the body and gelates, the gel moves down by gravity as time goes by. Therefore, the effective ingredient might not remain on the affected area sufficiently or bacteria might grow in accumulated gel at the bottom to cause an infection.
Furthermore, there are some ways of using a blood product or chemical substance to make an adhesion-preventing material firmly contact to organs or the like, although the handling might be difficult with required control for highest safety.
JP 2012-187926 A discloses some ways of using a macromolecule structure having a laminate of water soluble resin layer and biodegradable resin layer made of polylactic acid or the like. However, the solubility and surgical handling (stickiness) of water soluble resin might not be sufficiently controlled.
Thus, there are many reports about materials with respect to adhesion preventing of tissues, but none of them have a sufficient ability as adhesion-preventing material. Thus, it could be helpful to provide a material to prevent the adhesion in a tissue-repairing time as maintaining the strength without the above-described problems.
Specifically, it could be helpful to provide a laminated film comprising acetylated hyaluronic acid layer and a polylactic acid-based resin layer that is highly biocompatible and easy to handle, has good pasting ability and contact to an organ tissue and rarely induces infections.